Buggy code:
public ) { } private static int checkNextChar ( char [ ] typeName , char expectedChar , int pos , int length , boolean isOptional ) { } private static int encodeTypeSignature ( char [ ] typeName , int start , boolean isResolved , int length , StringBuffer buffer ) { } public static String createTypeSignature ( String typeName , boolean isResolved ) { } public static int getArrayCount ( char [ ] typeSignature ) throws IllegalArgumentException { } public static int getArrayCount ( String typeSignature ) throws IllegalArgumentException { } public static char [ ] getElementType ( char [ ] typeSignature ) throws IllegalArgumentException { } public static String getElementType ( String typeSignature ) throws IllegalArgumentException { } public static int getParameterCount ( char [ ] methodSignature ) throws IllegalArgumentException { } public static int getTypeSignatureKind ( char [ ] typeSignature ) { } public static int getTypeSignatureKind ( String typeSignature ) { } public static int getParameterCount ( String methodSignature ) throws IllegalArgumentException { } public static char [ ] [ ] getParameterTypes ( char [ ] methodSignature ) throws IllegalArgumentException { } public static String [ ] getParameterTypes ( String methodSignature ) throws IllegalArgumentException { } public static String [ ] getThrownExceptionTypes ( String methodSignature ) throws IllegalArgumentException { } public static char [ ] [ ] getThrownExceptionTypes ( char [ ] methodSignature ) throws IllegalArgumentException { } public static char [ ] [ ] getTypeArguments ( char [ ] parameterizedTypeSignature ) throws IllegalArgumentException { } public static String [ ] getTypeArguments ( String parameterizedTypeSignature ) throws IllegalArgumentException { } public static char [ ] getTypeErasure ( char [ ] parameterizedTypeSignature ) throws IllegalArgumentException { } public static String getTypeErasure ( String parameterizedTypeSignature ) throws IllegalArgumentException { } public static char [ ] [ ] getTypeParameters ( char [ ] methodOrTypeSignature ) throws IllegalArgumentException { } public static String [ ] getTypeParameters ( String methodOrTypeSignature ) throws IllegalArgumentException { } public static String getTypeVariable ( String formalTypeParameterSignature ) throws IllegalArgumentException { } public static char [ ] getTypeVariable ( char [ ] formalTypeParameterSignature ) throws IllegalArgumentException { } public static char [ ] [ ] getTypeParameterBounds ( char [ ] formalTypeParameterSignature ) throws IllegalArgumentException { } public static String [ ] getTypeParameterBounds ( String formalTypeParameterSignature ) throws IllegalArgumentException { } public static char [ ] getQualifier ( char [ ] name ) { } public static String getQualifier ( String name ) { } public static char [ ] getReturnType ( char [ ] methodSignature ) throws IllegalArgumentException { } public static String getReturnType ( String methodSignature ) throws IllegalArgumentException { } public static char [ ] getSignatureQualifier ( char [ ] typeSignature ) { } public static String getSignatureQualifier ( String typeSignature ) { } public static char [ ] getSignatureSimpleName ( char [ ] typeSignature ) { } public static String getSignatureSimpleName ( String typeSignature ) { } public static char [ ] getSimpleName ( char [ ] name ) { } public static String getSimpleName ( String name ) { } private static void appendSimpleName ( char [ ] name , int start , int end , StringBuffer buffer ) { } private static void appendArgumentSimpleNames ( char [ ] name , int start , int end , StringBuffer buffer ) { } public static char [ ] [ ] getSimpleNames ( char [ ] name ) { } public static String [ ] getSimpleNames ( String name ) { } public static char [ ] removeCapture ( char [ ] methodOrTypeSignature ) { } public static String removeCapture ( String methodOrTypeSignature ) { } public static char [ ] toCharArray ( char [ ] methodSignature , char [ ] methodName , char [ ] [ ] parameterNames , boolean fullyQualifyTypeNames , boolean includeReturnType ) { } public static char [ ] toCharArray ( char [ ] methodSignature , char [ ] methodName , char [ ] [ ] parameterNames , boolean fullyQualifyTypeNames , boolean includeReturnType , boolean isVargArgs ) { } public static char [ ] toCharArray ( char [ ] signature ) throws IllegalArgumentException { } private static int appendTypeSignature ( char [ ] string , int start , boolean fullyQualifyTypeNames , StringBuffer buffer ) { } private static int appendTypeSignature ( char [ ] string , int start , boolean fullyQualifyTypeNames , StringBuffer buffer , boolean isVarArgs ) { } private static int appendArrayTypeSignature ( char [ ] string , int start , boolean fullyQualifyTypeNames , StringBuffer buffer ) { } private static int appendCaptureTypeSignature ( char [ ] string , int start , boolean fullyQualifyTypeNames , StringBuffer buffer ) { } private static int appendArrayTypeSignature ( char [ ] string , int start , boolean fullyQualifyTypeNames , StringBuffer buffer , boolean isVarArgs ) { } private static int appendClassTypeSignature ( char [ ] string , int start , boolean fullyQualifyTypeNames , StringBuffer buffer ) { if ( start >= ( ( string . length ) - 2 ) ) { throw new IllegalArgumentException ( ) ; } char c = string [ start ] ; if ( ( c != ( Signature . C_RESOLVED ) ) && ( c != ( Signature . C_UNRESOLVED ) ) ) { throw new IllegalArgumentException ( ) ; } boolean resolved = c == ( Signature . C_RESOLVED ) ; boolean removePackageQualifiers = ! fullyQualifyTypeNames ; if ( ! resolved ) { removePackageQualifiers = false ; } int p = start + 1 ; int checkpoint = buffer . length ( ) ; int innerTypeStart = - 1 ; boolean inAnonymousType = false ; while ( true ) { if ( p >= ( string . length ) ) { throw new IllegalArgumentException ( ) ; } c = string [ p ] ; switch ( c ) { case Signature . C_SEMICOLON : return p ; case Signature . C_GENERIC_START : int e = Signature . appendTypeArgumentSignatures ( string , p , fullyQualifyTypeNames , buffer ) ; removePackageQualifiers = false ; p = e ; break ; case Signature . C_DOT : if ( removePackageQualifiers ) { buffer . setLength ( checkpoint ) ; } else { buffer . append ( '.' ) ; } break ; case '//' : if ( removePackageQualifiers ) { buffer . setLength ( checkpoint ) ; } else { buffer . append ( '//' ) ; } break ; case Signature . C_DOLLAR : innerTypeStart = buffer . length ( ) ; inAnonymousType = false ; if ( resolved ) { removePackageQualifiers = false ; buffer . append ( '.' ) ; } break ; default : if ( ( ( innerTypeStart != ( - 1 ) ) && ( ! inAnonymousType ) ) && ( Character . isDigit ( c ) ) ) { inAnonymousType = true ; buffer . setLength ( innerTypeStart ) ; <START_BUG> buffer . insert ( 0 , "new<seq2seq4repair_space>" ) ; <END_BUG>

Fix:
buffer . insert ( checkpoint , "new<seq2seq4repair_space>" ) ;